Arrow

Someone explain to me how a throttle body spacer could increase fuel economy and horsepower. It's just a spacer. Is this sales crap, or does that finger-thin hunk of metal actually do something?

Specific reference: HELIX PTP THROTTLE BODY SPACER

Black06GT40324

well the reason they say that is because the air going into the chamber is now swirling and they say that the motor performes better when the air is mixed up and not strait flowing

its kinda like those turbonator things you see on tv, same concept, just my take

CrazyAl

There are various things that a throttle body (or Carburetor) spacer can do:

First and perhaps formost, is that the spacer changes the length and volume of the intake tract. That's the space between the throttle butterfly and the actual engine intake valve. Playing with spacers is a lot like installing a different intake manifold with different runner lengths (only on a smaller scale). When you do this you change the resonance characteristics of the intake.

This works a lot like a trombone. When the trombone player moves the slide on the trombone, the notes change. This same thing can happen with the spacer: when you add the spacer you increase the length of the "intake pipe" a little bit, and this changes the behavior of airflow through it.

Is this good? Well, usually it's a trade-off. Longer intake passages are generally good for low RPM operation, whereas short passages are better for high RPM. Spacers can give you better performance, but usually only in certain areas.

Some spacers are made of plastic or phenolic (a composite material). These serve to block the flow of heat from the engine into the throttle body (or carburetor). This helps keep the intake air a little cooler. BUT that's not an issue on our cars because we already have a plastic intake manifold.

Some spacers have a series of notches cut into them. Supposedly this spins the intake air into a vortex, which helps atomization. I call BS on this one. First off, none of the spacers appear to have any kind of shape that really would affect all (or even the majority) of the intake air. I have fooled with similar things on a flowbench, and I am not conviced they do much. Second, you don't get something for nothing. What I mean by that is that IF the spacer somehow makes the air spin as it passes through it, that extra energy has to come from somewhere. The spacer doesn't have a fan or a motor or anything that adds this energy, so where would it come from? It would come from the air itself. That means the spacer would then act as a RESTRICTION that slows down the air in order to make it spin. Such a device might give a small boost in performance at low RPM, but it would be a hindrance at higher RPM.

Personally, I do NOT belive that a throttle body spacer does much on our cars. The reason is that modern engines that have been designed in the last several years (such as ours) have been through hours and hours of testing and simulation on complex computer systems. If changing the shape of the intake manifold that little bit would make extra HP, you can bet your ***** that Ford would have done so from the factory. (That's the same reason why aftermarket cams don't do much on these cars, whereas a cam could get you 100 HP easy on an older V8)

I think the reason why you see them for sale is becasue the sellers want to make a quick buck. I put them in the same category as the strut-tower braces. Years ago, on SOME cars, these parts were beneficial. They aren't a very good product for modern cars. BUT, they are easy to make, easy to install, and thus are a great product to sell becasue you've got a huge potential market. People expect them to do something becasue of "past performance", and they satisfy people's needs for a relatively cheap, easy to do, and very visible mod.

Booster

I just wonder why we see all that stuff on TV late at night, but not in the stores.

Arrow

I'm curious now.

It's such a cheap upgrade. Even if it only helps performance in one RPM range, and even if the benifits are negligable, it seems such a simple upgrade that I find it hard to pass up.

BTW, although I agree that Ford did a lot of testing to make a better engine, if that line of logic follows, why would we buy CAI's? Don't you think Ford could have found a better way to bring air in, from a cooler place, than where it does now? If so, kinda makes you wonder...

06triplevalve

Arrow-

The reason our cars do not come with a CAI is due to sound regulations (mostly). The government puts a restriction on the noise our eight cylindered little friends can make, and the CAI is not up to the task of masking that racket. Also, being a mass produced item, and due to reliability, as well as liability issues, they want the intake covered to protect the incoming air from junk. If Ford sold us a car with a CAI and some dimwit was spraying carb cleaner next to the intake (or worse yet, in!) with the car running you could have a real problem on your hands. With the standard box it's much tougher to do something dumb like that. Not that any of us would do that...

That said, I agree that if MOST parts made more power, then Ford woulda put it on to start with.

Now a supercharger, well, that's another story!

RL

CrazyAl

That is a good analysis of the CAI.

Keep in mind that many parts that Ford uses are a compromise of one sort or another. For example, the lower control arms on these cars are a known weak spot. Why did Ford do that? Well, their stamped metal construction is certainly cheap for Ford to make. Making nicer ones would entail a higher cost.

But, in the case of the manifold/spacer this isn't an issue. They could make a manifold with a different shape for NO additional cost.

I'm thinking that one of two things is true:

either the TBS doesn't do anything worth mentioning (on the 'Stang that is)
-or-
it's a tradeoff that Ford didn't want to make.

For example, perhaps it is worth more low-end power at the cost of high-end power. That's usually the way it is with intake tract dimension changes. When I said "intake tract changes can give you benefits but only in certain areas" what I meant to add, but forgot, is that they usually COST you HP elsewhere.

For example, a "tunnel ram" type of manifold for a carbureted engine has short runners. This gives you extra HP "up top" at the cost of HP at lower RPM ranges. On the other hand, a dual-plane manifold with long runners has the opposite effect: it makes more HP at low RPM, but less at higher RPM. Either one could be good (or bad) depending on what your application is--but neither one is "better" than anything else, it's just different.

ski

Gotta agree with CrazyAl.
A TBS slightly extends the length of the intake tract which in turn slightly increases low end torque and thus slightly improves throttle repsonse, but at the expense of restricting the high rpm A/F flow which slightly reduces high end hp.
However, when considering that Ford installed 3 valves per cylinder and VCT(variable cam timing) on the 2005+ 4.6L engines, it's evident what their priority was. They wanted gobs of high end A/F flow in order to produce big high end hp numbers. Installing a TBS would have restricted the high end flow, and thus would have reduced the maximum attainable high end hp.

Arrow

Okay, I've done some research, and I can see the validity of creating a vortex of air. However, I also see that 1 inch of ribbing (rifling) probably won't make much difference unless the air is really whipping through.

To that end, if creating a vortex is useful, maybe someone should make an intake pipe that's rifled all the way? One inch of rifling won't do much, but 3 feet of it would be far more effective. Plus, with all that added length, the ribbing could be smaller, reducing potential drag.

Just a though.

ski

No only is it very expensive to rifle the interior wall of a 3' long conduit, but it is also counterproductive as it will greatly increase the drag on the airflow, which in turn will greatly reduce the high rpm hp. This has been proven in tests conducted on several aftermarket 'vortex generators', which generate far less restriction than a 3' length of rifled tubing.

The analysis of the S197 Mustang's 4.6L N/A(naturally aspirated) engine is simple.
It's designed with 3 valves per cylinder and VCT that allow it to breathe freely at higher rpm's in order to develop max hp, but suffers from reduced low end torque due to it's small cubic inch displacement(281 cu. in.).
Charge motion plates are installed to help increase the low end torque. They are located at the end of each intake runner, and are partially closed in the low-mid range rpms in order to swirl the flow of the incoming air, and thus develop higher torque.
But it is just not a low rpm torque monster in its N/A configuration like the big cubic inch engines of old(383's, 390's, 426's, 427's, and 440's. Ahh...sweet memories. Oops, showing my age), and never will be. However, you can make it feel faster off the line by installing an aftermarket tune that improves throttle response by modifying the ECM's torque management algorithm, which in turn makes the throttle plate's DOM(degree of movement) more linear with the gas pedal's DOM. Or by installing lower rear gearing(3.73, 4.10, etc.) that increases the drivetrain's mechanical advantage.
But the botton line is that the only proven way to greatly increase this engine's low end torque is either by boring and stroking it to increase its displacement(do not know if that's even possible), or by installing either a supercharger, turbocharger, or nitrous system to increase the amount of oxygen flowing into the cylinders each second(supercharging probably has the greatest impact on increasing low end torque).